Abrading – Precision device or process - or with condition responsive... – By optical sensor
Reexamination Certificate
1999-05-28
2001-09-04
Banks, Derris H. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
By optical sensor
C451S005000
Reexamination Certificate
active
06283826
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an eyeglass lens grinding apparatus for grinding the periphery of an eyeglass lens.
An apparatus is known, in which a subject lens is clamped by two lens rotating shafts, the lens is rotated by synchronously rotating these two lens rotating shafts by mechanically linking them by means of pulleys, gears, and timing belts, and the lens is ground by moving the lens rotating shafts relative to an abrasive wheel.
In processing, a mounting jig such as a suction cup secured to the front surface side of the lens is fitted to a cup holder provided on one lens rotating shaft, the other lens rotating shaft having a lens holder is moved toward the cup holder to press and clamp the lens. An angle of rotation of the lens during grinding is controlled using a pulse motor which rotates the lens rotating shafts synchronously.
If the force (chuck pressure) with which the lens is pressed by the two lens rotating shafts is weak, the so-called axial offset occurs in which an actual axial angle of the lens is not coincident with an intended angle of rotation of the lens.
Major factors causing this axial offset are a processing error that occurs due to the deformation of a rubber portion of the mounting jig caused by the processing resistance applied by the abrasive wheel during lens grinding, and an error that occurs in the controlled angle of the axis of rotation of the lens due to an insufficient rigidity of a lens rotating mechanism section. The axial offset deteriorates the accuracy of the axial angle of the lens and hinders the accurate reproducibility of the finished shape.
The reduction of the axial offset depends solely on the reduction of the deformation amount of the rubber portion by increasing the chuck pressure to apply a strong pressure to the rubber portion of the mounting jig. However, if an excessively large chuck pressure is applied, the coating film or layer on the lens surface is damaged or broken and, in the case of a glass lens, the lens itself is broken.
SUMMARY OF THE INVENTION
In view of the above-described problems, it is an object of the present invention to provide an eyeglass lens grinding apparatus which makes it possible to effect highly accurate grinding by preventing an axial offset, lens breakage, and coating breakage.
The present invention provides the followings:
(1) An eyeglass lens grinding apparatus for grinding a periphery of a lens, the apparatus comprising:
processing means, having abrasive wheels, for processing the lens while depressing the lens onto at least one of the abrasive wheels or vice versa;
a first lens chuck shaft to which the lens is fixedly mounted through a lens fixing cup;
a second lens chuck shaft having a lens pressing holder, which is arranged coaxially with respect to the first lens chuck shaft;
rotating means for rotating the first lens chuck shaft;
chucking means for clamping the lens by relatively moving the second lens chuck shaft with respect to the first lens chuck shaft in a direction of an axis of rotation;
first detection means for detecting an angle of rotation of the second lens chuck shaft when the second lens chuck shaft is rotatingly driven by the first lens chuck shaft rotated by the rotating means in a state where the lens is clamped by the first and second lens chuck shafts; and
control means for controlling processing based on a result of detection by the first detection means;
(2) The eyeglass lens grinding apparatus according to (1), wherein the first and second chuck shafts are rotatable independently of each other.
(3) The eyeglass lens grinding apparatus according to (1), wherein the second lens chuck shaft is not rotated by the rotating means when the lens is not clamped, whereas the second lens chuck shaft is rotated in synchronism with the first lens chuck shaft by the rotating means when the lens is clamped.
(4) The eyeglass lens grinding apparatus according to (1), further comprising:
second detection means for detecting an angle of rotation of the first lens chuck shaft;
calculation means for obtaining an angular deviation between the angle of rotation detected by the first detection means and the angle of rotation detected by the second detection means;
varying means for varying processing pressure based on the angular deviation thus obtained.
(5) The eyeglass lens grinding apparatus according to (4), wherein the rotating means includes a pulse motor, and the second detection means detects the angle of rotation of the first lens chuck shaft driven by the pulse motor.
(6) The eyeglass lens grinding apparatus according to (4), wherein the processing means includes moving means, having a motor, for moving the first and second lens chuck shafts toward the abrasive wheels, and the varying means varies rotational torque of the motor based on the angular deviation thus obtained.
(7) The eyeglass lens grinding apparatus according to (1), wherein the processing means includes moving means for moving the first and second lens chuck shafts toward the abrasive wheels, and the control means controls the moving means based on the result of detection by the first detection means.
(8) The eyeglass lens grinding apparatus according to (7), wherein the control means controls the moving means so as to vary a axis-to-axis distance between a rotational axis of the lens and a rotational axis of the abrasive wheels.
(9) An eyeglass lens grinding apparatus for grinding a periphery of a lens, the apparatus comprising:
a processing device having abrasive wheels, which processes the lens while depressing the lens onto at least one of the abrasive wheels rotatingly driven by an abrasive wheel rotating motor, or vice versa;
a first lens chuck shaft to which the lens is fixedly mounted through a lens fixing cup;
a second lens chuck shaft having a lens pressing holder, which is arranged coaxially with respect to the first lens chuck shaft;
a rotating device having a motor and a transmission member which transmits rotational force of the motor to the first lens chuck shaft;
a chucking device which clamps the lens by relatively moving the second lens chuck shaft with respect to the first lens chuck shaft in a direction of an axis of rotation with a moving mechanism;
a first detector, which detects an angle of rotation of the second lens chuck shaft when the second lens chuck shaft is rotatingly driven by the first lens chuck shaft rotated by the rotating device in a state where the lens is clamped by the first and second lens chuck shafts; and
a controller, which controls processing based on a result of detection by the first detector.
(10) The eyeglass lens grinding apparatus according to (9), wherein the moving mechanism includes a motor and a motion-converting member which converts rotational motion of the motor to a linear motion in a direction of an axis about which the first and second lens chuck shafts are rotatable.
(11) The eyeglass lens grinding apparatus according to (9), wherein the first and second lens chuck shafts are rotatable independently of each other.
(12) The eyeglass lens grinding apparatus according to (9), further comprising:
a second detector, which detects an angle of rotation of the first lens chuck shaft;
wherein the controller obtains an angular deviation between the angle of rotation detected by the first detector and the angle of rotation detected by the second detector, and varies processing pressure based on the angular deviation thus obtained.
(13) The eyeglass lens grinding apparatus according to (12), wherein the motor included in the rotating device is a pulse motor, and the second detector detects the angle of rotation of the first lens chuck shaft driven by the pulse motor.
(14) The eyeglass lens grinding apparatus according to (12), wherein the processing device includes a moving device having a lens moving motor, which moves the first and second lens chuck shafts toward the abrasive wheels, and the controller controls rotational torque of the lens moving motor based on the angular deviation thus obtained.
(15) The eyeglass lens grinding a
Banks Derris H.
Nidek Co. Ltd.
Shakeri Hadi
Sughrue Mion Zinn Macpeak & Seas, PLLC
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